Hybrid PET/MRI as a tool to detect brown adipose tissue: Proof of principle

Obes Res Clin Pract. 2015 Nov-Dec;9(6):613-7. doi: 10.1016/j.orcp.2015.05.004. Epub 2015 Jun 4.


Objective: The purpose of this study was to assess the performance of (18)F-FDG hybrid PET/MRI to detect and localise the presence of metabolically active brown adipose tissue (BAT).

Methods: We retrospectively analyzed 197 consecutive (18)F-flurodeoxyglucose ((18)F-FDG) positron-emission tomographic (PET) and magnetic resonance imaging (MRI) images performed with a hybrid whole-body PET-MRI tomography in 192 patients. These patients were originally investigated mainly for oncological staging, in the absence of a cooling protocol. The presence of BAT was defined as a soft tissue structure that was larger than 4mm in diameter, had the characteristics of fat tissue on MRI and had a maximal standardised uptake value (SUV) of (18)F-FDG of at least 2.0. No specific MRI sequences for BAT detection were acquired.

Results: PET/MRI identified the presence of metabolically active BAT in 5 out of 192 patients (2.6%). BAT positive subjects were all female, significantly younger and with significantly lower body weight than BAT negative subjects.

Conclusions: Whole body hybrid PET/MRI allowed for the identification of BAT, with a low prevalence, comparable to previous retrospective PET/CT studies realised in the absence of a cooling protocol. The main advantages of the PET/MRI hybrid technique, as compared with PET/CT, includes a lower radiation burden, and the possibility to combine a multiparameter fat characterization by dedicated MRI sequences. Hybrid PET/MRI might represent the ideal tool for BAT evaluation.

Keywords: Brown adipose tissue; Magnetic resonance imaging; Obesity; Positron emission tomography.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue, Brown / anatomy & histology
  • Adipose Tissue, Brown / diagnostic imaging*
  • Adult
  • Aged
  • Cold Temperature
  • Female
  • Fluorodeoxyglucose F18 / administration & dosage
  • Fluorodeoxyglucose F18 / metabolism
  • Humans
  • Image Processing, Computer-Assisted
  • Incidence
  • Magnetic Resonance Imaging*
  • Male
  • Middle Aged
  • Multimodal Imaging / methods*
  • Positron-Emission Tomography* / methods
  • Radiopharmaceuticals / administration & dosage
  • Radiopharmaceuticals / metabolism
  • Reproducibility of Results
  • Retrospective Studies
  • Sensitivity and Specificity
  • Switzerland / epidemiology
  • Thermogenesis
  • Tissue Distribution
  • Tomography, X-Ray Computed
  • Whole Body Imaging


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18